JPH04238302A - Method for laying optical cable to sewerage and drain pipeline - Google Patents

Abstract

PURPOSE:To prevent the disconnection of the optical fibers in an optical cable by preventing the dirt flowing in a pipeline from hindering water flow without being caught by the optical cable and preventing the elongation of the optical cable by elongation of a coil spring when abnormal tension is applied on the optical cable. CONSTITUTION:The optical cable 15 is passed into the sewerage and drain pipeline 13 within a unit section segmented by impounding inlet chambers 11a, 11b as a pipeline junction container. The optical cable 15 is separated into the coated optical fibers 17 and a tension member 19 in a pipeline port 23. The tension member 19 is tensed by the coil spring 21 and is detained above the pipeline port 23, and the optical cable 15 is laid along the inside surface in the upper half part in the sewerage and drain pipeline 13.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of installing optical cables in sewage/drainage pipes, etc.

0002

[Prior Art] Generally, optical cables are installed either overhead or in cable conduits buried underground.
Recently, consideration has been given to installing this system inside sewage/drainage pipes. The reason for this is that sewage and drainage pipes reach every home, and by using these pipes, optical cables can be brought to each home at low cost and in a short period of time.

0003

[Problems to be Solved by the Invention] When installing optical cables in sewage/drainage pipes, the following points must be noted. The first point is to avoid simply running an optical cable into a sewage/drainage pipe, as there is a risk that the optical cable will get caught in debris, which will accumulate and obstruct the flow of water. The second point is that if the fluid resistance of the optical cable increases due to the accumulation of dust, or if the conduit is deformed, bent, or stretched due to ground subsidence or construction, abnormal tension will be applied to the optical cable and the optical fiber will break. This should be eliminated as there is a risk of this happening.

[0004] The third point is that when installing optical cables, construction equipment is installed on public roads, so it is necessary to make the installation as simple and quick as possible so as not to obstruct traffic. The fourth point is that optical cables and their supports do not get in the way when cleaning or inspecting sewage/drainage pipes. The fifth point is that when a failure occurs in the optical cable, it can be quickly replaced with a new cable.

[0005]

[Means for Solving the Problems] The present invention provides a method for laying optical cables in sewage/drainage pipes that solves the above-mentioned problems. Sewage/sewage area of unit area divided by
An optical cable is passed through the drainage pipe, and the tension member of the optical cable is tensioned at both ends of the drainage pipe by a coil spring connected to at least one end of the optical cable. It is characterized by being installed above the water surface in normal conditions (preferably in the upper half) and close to the inner surface of the pipe. In the case of sewage/drainage pipes, the water surface under normal conditions is at a level of about 1/10 of the inner diameter of the pipe from the bottom of the inner surface of the pipe. The pipe is designed so that even when the water level increases due to rainfall, the water level is only about half of the pipe's inner diameter. That is, under normal conditions, the inner surface of the pipe is submerged in water to only about 1/10 of the inner diameter of the pipe. The area that is submerged in water under normal conditions is called the tube bottom. That is, in the present invention, the optical cable is laid close to the inner surface of the pipe in an area other than the bottom of the pipe (preferably in the upper half of the pipe).

[0006]

[Function] In the present invention, the optical cable is laid close to the inner surface of the sewage/drainage pipe above the normal water level in the sewage/drainage pipe to prevent dust from getting caught in the optical cable and This is to facilitate cleaning and inspection of the inside of the pipe. In addition, the reason why tension members of the optical cable are applied tension to both ends of the sewage/drainage pipe is to eliminate cable support in the middle, making installation easier and faster, and to make it easier to replace the optical cable in the event of a failure. This is to make it easier. Furthermore, the reason why tension is applied through the coil spring is to prevent the optical fiber from breaking by suppressing the extension of the optical cable by stretching the coil spring when the optical cable is pulled abnormally for some reason.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the method for installing optical cables in sewage/drainage pipes according to the present invention will be described in detail with reference to the drawings.

FIGS. 1 and 2 show an embodiment of the laying method according to the present invention. Reference numerals 11a and 11b are boxes serving as pipe relay containers, and 13 is a sewage/drainage pipe buried between the boxes 11a and 11b. One cell 11a is installed, for example, on the premises of a home, and the other cell 11b is, for example, part of a public sewer system installed on a road.

First, the optical cable 15 is drawn into the sewage/drainage pipe 13 separated by the squares 11a and 11b. For example, as shown in FIG. 3, the optical cable 15 is composed of an optical cable main body 17 and a tension member 19, and is covered with a sheath 20 made of plastic or the like. The optical cable 15 is connected to the optical cable main body 1 within the spaces 11a and 11b.
7 and a tension member 19, and tension is applied to the tension member 19 by a coil spring 21.
Hold it above 3.

The details of the retaining method are as follows, for example. First, the retaining plate 25 is fixed to the walls of the cells 11a and 11b using anchor bolts 27. Retaining plate 2
Reference numeral 5 is a rectangular flat plate having a semicircular cutout so as to match the conduit port 23. A semicircular stopper 29 is welded to the front surface of the flat plate along the semicircular notch.

A cable guide fixture 31 is attached to this stopper 29, and a cable guide 33 is attached to the cable guide fixture 31. The cable guide fitting 31 and the cable guide 33 have the structures shown in FIGS. 4 and 5. That is, the cable guide fixture 31 is made of plastic or rubber, and includes a horseshoe-shaped groove 31a that holds the cable guide 33, and a stopper 29.
A round hole 31b is formed to be attached to. The cable guide 33 is a metal piece with a semicircular cross section, and one end is processed into a curved shape.

On the other hand, the end of the tension member 19 of the optical cable 15 is folded back into a loop shape and tightened with a clamp 35. Then, connect the optical cable 15 to the cable guide 3.
1, attach the coil spring 2 to the coil spring fixing bolt 39.
One end of the tension member 19 is fixed, and the folded part of the tension member 19 is hooked on the other end. In this state, the tension member 19 is set to a normal tension, for example, 30 kg.

As shown in FIG. 2, the tension plate 23 used in this embodiment has a tension of 10 kg, for example, of the coil spring 21.
The lengths corresponding to 30Kg and 50Kg are displayed. This is convenient for checking the tension of the tension member 19. The optical cable main body 17 in one of the cells 11a is pulled out from the appropriately protected cell 11a and brought into the house, and the optical cable main body 17 in the other cell 11b is connected to the main optical cable within that cell 11b, for example. be done.

According to the method described above, the optical cable 15
can be laid close to the inner surface of the upper half of the sewage/drainage pipe 13 while maintaining the desired tension. After the optical cable is laid, when the conduit is deformed, bent, stretched, etc. due to ground subsidence, construction work, etc. and abnormal tension is applied to the optical cable 15, the coil spring 21 is stretched to prevent the optical cable 15 from stretching. If it is discovered that the coil spring 21 has been stretched beyond a predetermined length, the set tension of the tension member 19 is corrected to the normal tension.

FIG. 6 shows another embodiment of the method for laying optical cables in sewage/drainage pipes according to the present invention. In FIG. 6, parts having the same functions as those in FIG. 1 are given the same reference numerals. In this embodiment, a coil spring 21 is attached to the wall opposite the conduit opening 23 to hold the tension member 19 of the optical cable 15 in the box 11. Further, in this embodiment, in order to hold the tension member 19 in place, a retainer 39 is used which ties the tension member 19 in a figure 8 shape and holds it in place. With this method as well, the optical cable can be laid close to the inner surface of the upper half of the conduit while maintaining the desired tension.

FIG. 7 shows still another embodiment of the method for laying optical cables in sewage/drainage pipes according to the present invention. In this embodiment as well, parts having the same functions as those in FIG. 1 are denoted by the same reference numerals. In this embodiment, an optical cable 15 passes through a square 11, and tension members 19 of the optical cable 15 are held back on both sides of the square 11. Optical cable body 1
7 is housed in a loop shape within the guide roller 41 with sufficient extra length.

FIGS. 8 and 9 show still another embodiment of the laying method of the present invention. In this embodiment, a retainer 39 for retaining the tension member 19 of the optical cable 15 and a coil spring 21 are attached to the sewage/drainage pipe 10 near the box 11.
It was installed at the top of the interior. Therefore, in this embodiment, an L-shaped fixture 43 is used.

The fixing fitting 43 has a bolt hole 4 at its upper end.
A hole 49 at the tip is fixed to the box 11 by an anchor bolt 47 passed through the hole 5 and extends into the sewage/drainage pipe 13.
A coil spring 21 can be hooked onto the coil spring 21. Further, the fixing fitting 43 has a cable support ring 51 at its bent portion, and the optical cable main body 17 separated from the tension member 19 is attached to the support ring 51.
It is drawn into the passage 11. Furthermore, the fixture 43 has a screw hole 53 into which a tension adjustment screw 55 is screwed. Tension adjustment screw 5
5 is screwed so that its tip abuts against the wall surface of the square 11, and by adjusting the screwing amount, the fixing metal fitting 43 is bent and the tension of the coil spring 21 is adjusted.

If the coil spring 21 and the retainer 39 are installed inside the sewage/drainage pipe 13 as in this embodiment, there will be no obstructions in the box 11, so the box 1
There is an advantage that cleaning etc. inside 1 can be performed more easily. Although not shown, the other end of the sewage/drainage pipe 13 may have the same structure as above, or may omit the coil spring. In other words, the coil spring can be provided only on one end side.

[0020] When a retaining device including a coil spring is provided at only one end of the sewage/drainage pipe, it is preferably provided at the upstream end of the sewage/drainage pipe. This is because if the coil spring is provided only at the downstream end, there is a risk that dirt and the like will get caught there and block the sewage/drainage pipe. If it is provided only at the upstream end, even if large debris or the like that gets caught in the coil spring flows, it will collect in the chamber and will not enter the pipe line, so it can be easily removed.

[0021]

Effects of the Invention As explained above, according to the present invention, since the optical cable is laid close to the inner surface of the pipe above the water level in the normal state in the sewage/drainage pipe, the garbage flowing inside the pipe can be prevented. There is no risk of getting caught in the optical cable, so water flow is not obstructed, and cleaning and inspection inside the sewage/drainage pipes can be easily performed. In addition, since the tension members of the optical cable are held in place by applying tension to both ends of the sewage/drainage pipe, there is no need to support the cable in the middle, making it easy to install the cable in a short time. can be easily replaced. Furthermore, since tension is applied to the tension member of the optical cable via a coil spring, when the optical cable is pulled abnormally for some reason, the coil spring stretches, suppressing the extension of the optical cable and preventing the optical fiber from breaking. be able to.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of the method for installing optical cables in sewage/drainage pipes according to the present invention.

FIG. 2 is a sectional view taken along line A-A in FIG. 1.

FIG. 3 is a cross-sectional view showing an example of an optical cable.

FIG. 4 is a front view of the cable guide and its attachment.

FIG. 5 is a side view of FIG. 4.

FIG. 6 is a sectional view showing another embodiment of the present invention.

FIG. 7 is a sectional view showing still another embodiment of the present invention.

FIG. 8 is a sectional view showing still another embodiment of the present invention.

9 is a perspective view of fixing fittings and the like used in the embodiment of FIG. 8. FIG.

[Explanation of symbols]

11, 11a, 11b: Masu 13: Sewage/drainage pipe line 15: Optical cable 17: Optical cable body 19: Optical cable tension member 21: Coil spring 23: Pipe opening 25:
Retaining plate 35: Tension member clamp 43
:Fixing bracket 55:Tension adjustment screw

Claims (1)

[Claims] [Claim 1] An optical cable is passed through a sewage/drainage pipe in a unit section separated by a pipe relay container such as a handhole or a manhole, and at least tension members of the optical cable are connected at both ends of the sewage/drainage pipe. A sewage/drainage pipe characterized in that a coil spring connected to one end side of the sewage/drainage pipe is used to apply tension to the optical cable, thereby laying the optical cable close to the inner surface of the sewage/drainage pipe above the water surface under normal conditions within the sewage/drainage pipe. How to lay optical cables to roads.